drivers/connector/cn_queue.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  cn_queue.c
0004  *
0005  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
0006  * All rights reserved.
0007  */
0008
0009 #include <linux/kernel.h>
0010 #include <linux/module.h>
0011 #include <linux/list.h>
0012 #include <linux/workqueue.h>
0013 #include <linux/spinlock.h>
0014 #include <linux/slab.h>
0015 #include <linux/skbuff.h>
0016 #include <linux/suspend.h>
0017 #include <linux/connector.h>
0018 #include <linux/delay.h>
0019
0020 static struct cn_callback_entry *
0021 cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name,
0022                   const struct cb_id *id,
0023                   void (*callback)(struct cn_msg *,
0024                            struct netlink_skb_parms *))
0025 {
0026     struct cn_callback_entry *cbq;
0027
0028     cbq = kzalloc(sizeof(*cbq), GFP_KERNEL);
0029     if (!cbq) {
0030         pr_err("Failed to create new callback queue.\n");
0031         return NULL;
0032     }
0033
0034     refcount_set(&cbq->refcnt, 1);
0035
0036     atomic_inc(&dev->refcnt);
0037     cbq->pdev = dev;
0038
0039     snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
0040     memcpy(&cbq->id.id, id, sizeof(struct cb_id));
0041     cbq->callback = callback;
0042     return cbq;
0043 }
0044
0045 void cn_queue_release_callback(struct cn_callback_entry *cbq)
0046 {
0047     if (!refcount_dec_and_test(&cbq->refcnt))
0048         return;
0049
0050     atomic_dec(&cbq->pdev->refcnt);
0051     kfree(cbq);
0052 }
0053
0054 int cn_cb_equal(const struct cb_id *i1, const struct cb_id *i2)
0055 {
0056     return ((i1->idx == i2->idx) && (i1->val == i2->val));
0057 }
0058
0059 int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
0060               const struct cb_id *id,
0061               void (*callback)(struct cn_msg *,
0062                        struct netlink_skb_parms *))
0063 {
0064     struct cn_callback_entry *cbq, *__cbq;
0065     int found = 0;
0066
0067     cbq = cn_queue_alloc_callback_entry(dev, name, id, callback);
0068     if (!cbq)
0069         return -ENOMEM;
0070
0071     spin_lock_bh(&dev->queue_lock);
0072     list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
0073         if (cn_cb_equal(&__cbq->id.id, id)) {
0074             found = 1;
0075             break;
0076         }
0077     }
0078     if (!found)
0079         list_add_tail(&cbq->callback_entry, &dev->queue_list);
0080     spin_unlock_bh(&dev->queue_lock);
0081
0082     if (found) {
0083         cn_queue_release_callback(cbq);
0084         return -EINVAL;
0085     }
0086
0087     cbq->seq = 0;
0088     cbq->group = cbq->id.id.idx;
0089
0090     return 0;
0091 }
0092
0093 void cn_queue_del_callback(struct cn_queue_dev *dev, const struct cb_id *id)
0094 {
0095     struct cn_callback_entry *cbq, *n;
0096     int found = 0;
0097
0098     spin_lock_bh(&dev->queue_lock);
0099     list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
0100         if (cn_cb_equal(&cbq->id.id, id)) {
0101             list_del(&cbq->callback_entry);
0102             found = 1;
0103             break;
0104         }
0105     }
0106     spin_unlock_bh(&dev->queue_lock);
0107
0108     if (found)
0109         cn_queue_release_callback(cbq);
0110 }
0111
0112 struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *nls)
0113 {
0114     struct cn_queue_dev *dev;
0115
0116     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
0117     if (!dev)
0118         return NULL;
0119
0120     snprintf(dev->name, sizeof(dev->name), "%s", name);
0121     atomic_set(&dev->refcnt, 0);
0122     INIT_LIST_HEAD(&dev->queue_list);
0123     spin_lock_init(&dev->queue_lock);
0124
0125     dev->nls = nls;
0126
0127     return dev;
0128 }
0129
0130 void cn_queue_free_dev(struct cn_queue_dev *dev)
0131 {
0132     struct cn_callback_entry *cbq, *n;
0133
0134     spin_lock_bh(&dev->queue_lock);
0135     list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)
0136         list_del(&cbq->callback_entry);
0137     spin_unlock_bh(&dev->queue_lock);
0138
0139     while (atomic_read(&dev->refcnt)) {
0140         pr_info("Waiting for %s to become free: refcnt=%d.\n",
0141                dev->name, atomic_read(&dev->refcnt));
0142         msleep(1000);
0143     }
0144
0145     kfree(dev);
0146     dev = NULL;
0147 }